Radiofrequency energy is used in order to treat pain radiating from nerves in the spine. Several prior-art approaches exist in order to target an RF probe at the desired target location. However, regardless of the approach used, a limitation of RF techniques is that the lesion forms immediately adjacent to the probe tip. Hence the efficacy of the treatment is dependent upon the probe tip being in contact with or in close proximity to the target nerve. The treatment may be ineffective if the probe is positioned in the general area of the target nerve but not adjacent to the nerve. This has been outlined in Bogduk et al. (Neurosurgery, 20(4): 529-535, 1987) as the reason for low success rate of RF neurotomy in the spine, “despite the accurate placement of electrodes onto anatomically correct target points, the lesions may not fully incorporate the nerve. The electrode tip may have rested close to the nerve. However, RF electrodes coagulate circumferentially and only minimally distally, therefore the lesion may have been placed superficial to the nerve.” This problem is not limited to a perpendicular approach, as in the parallel approach even though “an electrode lying parallel to the nerve is more likely to incorporate the nerve . . . this modification relies critically on the accurate placement of the electrode”. Hence, the success of RF lesioning in the spine is dependent on the accurate positioning of the probe at the target nerve.
The thoracic region of the spine is a stable structure; thus a high prevalence of thoracic pain would not be expected. However, it has been shown that between 15 and 24% of people suffering from spinal pain experience upper back/thoracic pain (Linton et al., 1998; Manchikanti and Pampati, 2002). Facet joint pain accounts for 42% to 48% of patients with chronic thoracic pain (Manchikanti et al., 2004; Manchikanti et al., 2002). In summary, thoracic facet pain represents 6 to 12% of all spinal pain. Thus the present invention is directed to treating pain in the thoracic region of the spine.